Here is something from St. Ambrose, bishop of Milan (c. 340 - April 4, 397), regarding why Christians struggle but unbelievers seem to have a care-free, easy life. This, by the way, is the atheists' and even the Satanists' boast about why their "belief" is the preferred one. Ambrose reminds us why we struggle and, more importantly, the reward that awaits for those who struggle.
Ambrose's observations should also be compared with Psalm 73.
"Perhaps you say, Why are the wicked joyous? Why do they live in luxury? Why do they not toil with me? it is because they who have not put down their names to strive for the crown are not bound to undergo the labours of the contest. They who have not gone down into the race-course do not anoint themselves with oil nor get covered with dust. For those whom glory awaits trouble is at hand. The perfumed spectators are wont to look on, not to join in the struggle, nor to endure the sun, the heat, the dust, and the showers....
"They, then, who have devoted themselves to pleasures, luxury, robbery, gain, or honours are spectators rather than combatants. They have the profit of labour, but not the fruits of virtue. They love their ease; by cunning and wickedness they heap up riches; but they will pay the penalty of their iniquity, though it be late. Their rest will be in hell, yours in heaven; their home in the grave, yours in paradise." ("On the Duties of the Clergy," Selections from Book 1, chapter 16, paragraphs 60 and 61)